THE PETROLEUM RESOURCES OF THE 

UNITED STATES 


BY 

RALPH ARNOLD 


FROM THE SMITHSONIAN REPORT? FOR 1916, PAGES 273-287 



(Publication 2459) 


WASHINGTON 

GOVERNMENT PRINTING OFFICE 
1917 
















■ 



THE PETROLEUM RESOURCES OF THE 

UNITED STATES 


BY 

RALPH ARNOLD 

\\ 


FROM THE SMITHSONIAN REPORT FOR 1916, PAGES 273-287 


♦ 



(Publication 2459) 



WASHINGTON 

GOVERNMENT PRINTING OFFICE 
1917 






























THE PETROLEUM RESOURCES OF THE UNITED 

STATES. 1 


By Ralph Arnold. 


INTRODUCTION. 

In 1908 when the agitation for the conservation of our mineral 
and other natural resources was at its height, a paper was prepared 
by Dr. David T. Day on “ The Petroleum Resources of the United 
States." 2 It was the privilege of the writer to contribute some of 
the data upon which Dr. Day based his conclusions. Since the prep¬ 
aration of that article much development work has been done in 
this country, new fields have been opened up, and the possibilities 
of the older fields have been more closely studied. The present paper 
is intended as a revision of Dr. Day’s thesis in view of the latest in¬ 
formation pertaining to the subject. The writer wishes to acknowl¬ 
edge his indebtedness to the following, among others, who have 
contributed data used in the preparation of these estimates: James 
II. Gardner, M. J. Munn, Prof. L. C. Glenn, Prof. G. D. Harris, 
and Richard R. Hice. 

EXTENT OF THE PETROLEUM FIELDS. 

The oil fields of the United States usually are classified as the 
Appalachian, Lima-Indiana, Illinois, Mid-Continent, Gulf, Rocky 
Mountain, California, and Alaska. 

Appalachian field .—The Appalachian field extends from south¬ 
western New York, through western Pennsylvania, southeastern 
Ohio, West Virginia, and eastern Kentucky, into northern Ten¬ 
nessee. The formations yielding the oil throughout this field in¬ 
clude those of the Devonian and Carboniferous. The oil occurs 
along the axes and on the flanks of anticlines, parallel in general 
with the strike of the Appalachian Mountains, and on minor ter¬ 
races or other structures associated with them. Occasionally it has 


1 Reprinted by permission from Economic Geology, Vol. 10, No. 8, December, 1915. 

2 Bull. U. S. Geol. Survey, No. 394, pp. 30-50, 1909. 


273 





274 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1016. 

been found in waterless synclines. The reservoir rocks are prin¬ 
cipally sandstones and coarse sediments. The oil from this field 
is of the best quality in the world, yielding a high percentage of 
the lighter oils such as gasoline and kerosene, and is utilized entirely 
for refining. It is of paraffin base and varies in gravity from 25° 
to 50° Beaume (0.9032 to 0.7778 sp. gr.), the heavier grades coming 
only from the southern end of the field. The price of the “ Penn¬ 
sylvania grade ” oil is always high, ranging up to $2.50 per barrel. 
The average daily production of the w-ells is low, being 0.2 to 0.4 
barrels in 1911. This field is almost completely developed except the 
portions in Kentucky and Tennessee, and even here recent pros¬ 
pecting has resulted negatively in a majority of cases. 

Lima-Indiana field .—The Lima-Indiana field covers a considerable 
portion of northwestern Ohio and eastern Indiana. The oil is 
derived from the Ordovician, Silurian, and Carboniferous, largely 
from the Trenton limestone, the reservoir rock being porous dolo- 
mitic lenses or beds or sandstones. Favorable structures, such as 
half domes, terraces, etc., on the flanks of the Cincinnati uplift, 
usually harbor the commercial deposits. The oil is of paraffin base, 
varies in gravity from 30° to 35° Beaume (0.8750 to 0.8484 sp. gr.), 
carries a little sulphur, and is utilized entirely for refining purposes. 
The average initial daily production of the wells up to 1911 was 15.5 
barrels; the average daily production per well was 0.7 barrel for 
that year. This field also is practically outlined, although new pools 
are even yet being occasionally discovered. 

Illinois field —The Illinois field occupies a strip of territory along 
the La Salle anticline in the southeastern part of the State. It also 
extends a short distance into Indiana. The oil is derived largely 
from the Pennsylvanian and a little from the upper Mississippian 
(both Carboniferous), and occurs principally in well-defined sand¬ 
stone horizons along the crest of the asymmetric La Salle anticline. 
Impregnation is governed locally by the lithology. A little of the 
oil comes from limestone. The oil is of paraffin base, although 
locally carrying some asphalt, ranges in gravity from 28° to 39° 
Beaume (0.8860 to 0.8284 sp. gr.), and is used principally for re¬ 
fining purposes. The average initial daily production up to 1911 
was 63 barrels; the average daily production of the individual wells 
for the same year was 4.2 barrels. With the exception of some 
possible territory in the western part of the State the Illinois pro¬ 
ductive area is well defined at the present time. 

Mid-Continent field .—The Mid-Continent field comprises the pools 
in Oklahoma, southeastern Kansas, and northern Texas. The oil 
is secured from the sandstones of the Pennsylvania (Carbonifer¬ 
ous) formations in domes, half domes or terraces, and local anti¬ 
clines on the flanks of the great Ozark uplift. The oil is of paraffin 


PETROLEUM RESOURCES—ARNOLD. 


275 


base, varying in gravity from 27° to 41° Beaume (0.8917 to 0.8187 
sp. gr.), and is used for refining. It is piped to the Gulf and also 
to Indiana and other eastern States. The development in this field 
has been phenomenal during the past few years, some of the pools 
being exceedingly productive. The average initial daily production 
of the wells in 1911 was 119 barrels; the average daily production 
8.6 barrels. A fair percentage of the region embraced in this field 
yet remains to be prospected, the bulk of the untested land lying 
in Texas. 

Gulf field .—The Gulf field includes the pools lying along the 
coastal plain of Louisiana and Texas. The oil occurs for the most 
part in domes or quaquaversals associated with salt and gypsum 
deposits. The age of the containing rocks ranges from Cretaceous 
to Quaternary. The reservoir rock is usually porous dolomitic lime¬ 
stone or sandstone. The oil of northern Louisiana occurs in Cre¬ 
taceous and Eocene rocks along an uplift or fold. The oils of the 
Gulf field vary greatly in composition; those in the strictly coastal 
belt vary from 15° to 27.7° Beaume (0.9655 to 0.8878 sp. gr.) and are 
of asphalt base; those of northern Louisiana vary from 25° to 43.6° 
Beaume (0.9031 to 0.8065 sp. gr.) and are of paraffin base. Sulphur 
usually accompanies the heavy oil. The lighter oils are used for re¬ 
fining, the heavier for fuel. Some of the individual wells have been 
exceedingly productive, a daily flow of 75,000 barrels being recorded 
for one at least. The pools usually are quite short-lived. In 1911 
the average initial daily flow for the Gulf coastal pools was 257 
barrels; for northern Louisiana, 1,176 barrels; the daily average 
for the field, 60 barrels. Some territory still remains untested in this 
field. 

Rocky ‘Mountain field .—The Rocky Mountain field embraces pools 
in Wyoming and Colorado and as yet untested deposits in Utah and 
New Mexico. The oil occurs in beds of Carboniferous, Triassic (?), 
and Cretaceous age, nearly always in sandstone interbedded with 
shale, though occasionally in fracture zones. Typical dome structure 
is the most favorable location, but occasionally commercial deposits 
occupy monoclines or interrupted monoclines. The oils from the 
older formations vary in gravity from 18° to 24° Beaume (0.9459 to 
0.9091 sp. gr.), are of asphalt base, and are used largely for fuel; 
those from the Cretaceous vary from 32° to 48° Beaume (0.8642 to 
0.7865 sp. gr.), are of paraffin base, and are refined, yielding high per¬ 
centages of gasoline, kerosene, and distillates. The productivity of 
individual wells usually is not large, the average daily yield per well 
being about 25 barrels in 1913. The potentialities of the Rocky 
Mountain field are not great, unless the extensive deposits of oil 
shale of northwestern Colorado and northeastern Utah are taken 


276 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1916. 

into account. As these deposits will require a distillation process 
for the recovery of their oil contents, they are not included under the 
head of free oil deposits. 

California field. —California is the greatest producer of petro¬ 
leum of any State in the Union. It secures its oil from rocks of 
Cretaceous to late Tertiary age, the great bulk coming from the 
Miocene. Nearly every type of structure peculiar to the coast ranges 
yields commercial quantities of oil, anticlines, domes, plunging anti¬ 
clines, monoclines, and fault zones being the principal sources. The 
reservoir rocks usually are sand and sandstone, though fracture 
joints in shale hold oil in at least one district. The oil is practically 
all of asphalt base, although paraffin up to 4 per cent is found in a 
little of the oil from the Cretaceous and Eocene. The oil varies in 
gravity from 12° to 35° Beaume (0.9859 to 0.8484 sp. gr.), about 70 
per cent of it being topped or refined. Much of the heavy oil is used 
for fuel and road dressing. The productivity of individual wells 
has reached as high as 58,000 barrels daily; the average daily produc¬ 
tion per well was 45.2 barrels in 1913. The oil districts of Cali¬ 
fornia are practically outlined to-day and little in the way of addi¬ 
tional acreage is to be expected in the future. 

Alaska field .—Small quantities of oil have been obtained from 
the Jurassic rocks of western Alaska and the lower Tertiary of 
eastern Alaska. The oil occurs in sandstone along well-defined and 
sometimes faulted anticlines. The oil varies in gravity from 39° to 
45.9° Beaume (0.8284 to 0.7958 sp. gr.) and is of an excellent refining 
grade. The wells so far drilled are small producers. The commercial 
productivity of the Alaskan deposits yet remains to be proven. 

Other fields .—In addition to the States mentioned as occupying 
the above fields, oil occurs in small quantities in Michigan (a con¬ 
tinuation of the Petroleo, Canada, field) and Missouri (a continuation 
of the Oklahoma conditions). These States and Alaska together 
produced but 7,792 barrels in 1914. Alabama and Mississippi also 
are said to have possibilities. 

IMPORTANCE OF THE UNITED STATES AS COMPARED WITH OTHER 

COUNTRIES. 

The following table, compiled under the supervision of J. D. 
Northrop, of the United States Geological Survey, 1 giving the pro¬ 
duction of crude petroleum in 1914 and from 1857 to 1914, in barrels, 
illustrates the relative importance of the various oil-producing coun¬ 
tries of the world. 


1 Mining and Scientific Press, Aug. 14, 1915, p. 248. 




PETROLEUM RESOURCES-ARNOLD. 


277 


Table I.— World's production of crude petroleum in 1914 and 1857 to 1914, with 
percentage of production by countries, in barrels of J f 2 gallons. 


Country. 


United States. 

Russia. 

Mexico. 

Roumania. 

Dutch East Indies 

India. 

Galicia. 

Japan. 

Peru. 

Germany. 

Egypt. 

Trinidad. 

Canada. 

Italy. 

Other countries... 

Total. 


1914 


Production. 

Per cent. 

265, 762,535 

66.36 

67,020,522 

16.74 

21,188,427 

5.29 

12,826,579 

3.20 

i 12, 705,203 

3.17 

2 8,000,000 

2.00 

2 5,033,350 

1.26 

3 2,738,378 

.68 

1,917, 802 

.48 

2 995,764 

.25 

777,038 

.19 

643,533 

.16 

214, 805 

.05 

39,543 

.01 

4 620,000 

.16 

400,483,489 

100.00 


1857-1914 


Production. 

Per cent. 

3,335,457,140 

59.63 

1,622,233, 845 

29.00 

90,359,869 

1.62 

117,982,474 

2.11 

138,278,392 

2.47 

73.979,919 

1.32 

131,873,601 

2.36 

27,051,158 

.48 

14,306,972 

.26 

12,965.569 

.23 

1,086,728 

.02 

2,069,430 

.04 

23,493,610 

.42 

802,229 

.01 

1,322,000 

.03 

5,593,262,936 

100.00 


1 Includes British Borneo. 3 Includes Formosa. 

2 Estimated. 4 Includes 600,000 barrels produced in Argentina. 


The relative importance of the States in the Union is shown in 
the accompanying table, which gives the marketed production for the 
year 1914. In the case of two of the States at least, the marketed 
production is below the estimated production, the discrepancy being 
accounted for by oil put in storage. The actual production of Cali¬ 
fornia was probably around 103,000,000 barrels, with possibly 
7,000,000 barrels a shut in,” which might have been produced. The 
estimated production of Oklahoma was 98,000,000 barrels. 


Table IT .—Production of petroleum in the United States, by States, in 1914 and 

1857 to 1914, in barrels of 42 gallons. 



1914 

1857-1914 

Alaska. 

0) 

99,775,327 
222,773 
21,919, 749 
1,335,456 
3,103,585 
502,441 
14,309,435 
0) 

(0 


California. 

741, 273,559 
10,649,143 
232,326,616 
102, 823,798 
28,5-17,074 
9,095,970 
89,895, 433 
72, 712 

Colorado. . 

Illinois. 

Indiana. 

Kansas. 

Kentucky. 

Louisiana. 

Michigan. 

Missouri. 

New Mexico. 


New York. . 

938,974 
8,536,352 
73,631,724 
8,170,335 
20,068,184 
9,680,033 
3,560,375 
7.792 

( 2 ) 

432,762,004 
461,833,466 
754,180,215 
203,799,381 
260,232,815 
7,964,944 

Ohio. 

Oklahoma... 

Pennsylvania. 

Texas. 

West Virginia. . 

Wyoming. 

Other. . 

Total.. . . . 


265,762,535 

3,335, 457,130 



1 Included in “Other.” 2 Included in Pennsylvania. 


FACTORS GOVERNING THE PRODUCTION OF PETROLEUM. 

Before entering into a discussion of the probable future production 
of petroleum in the United States, it will be well to outline the various 
factors which govern this production. These factors may be divided 
into two groups, natural and artificial. 

73839°— sm 191G-19 


































































278 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1916. 


A. NATURAL FACTORS. 

1. Pressure. —The pressure exerted on the oil in its underground 
reservoir may be hydrostatic, hydraulic, or gas; it may be coexten¬ 
sive with the field or pool, in which case it is called u field pressure,” 
or it may be exceedingly local in extent, when it is called u local ” or 
u well pressure.” Pressure in oil wells varies from 0 to over 2,000 
pounds per square inch, usually declining as the field or well grows 
old. Other things being equal, the production varies with the pres¬ 
sure. 

2. Viscosity. —Production varies inversely with the viscosity, and 
since the viscosity in general increases with the specific gravity (in¬ 
creases inversely with the Beaume degrees) it may be said that, other 
conditions being equal, the production varies inversely with the spe¬ 
cific gravity of the oil. Natural petroleums vary from substances as 
fluid as water (low viscosity) to those having the consistency of u cold 
molasses” (high viscosity), or even to those possessing the properties 
of solids. 

3. Thickness and extent of reservoir rocks. —The production varies 
with the thickness and extent of the reservoir rock. The thickness of 
the pay streaks may vary from 2 feet, as in some fields of the eastern 
United States, to over 200 feet, as in some California fields. The 
lateral extent of the layer or lens may be from a few feet to several 
miles. 

4. Porosity of reservoir rocks. —Production varies inversely with 
the porosity within certain limits. In uniformly grained rocks the 
coarser the grain of the reservoir the less is the actual porosity; but 
the larger the size of the interstices the less is the friction surface per 
unit of oil. Therefore, coarse sediments are really less porous and 
consequently hold less oil, but they give it up more readily than fine 
sediments and usually give a greater ultimate yield per unit of 
volume. Beservoir rocks may be fine shale to the coarsest conglo¬ 
merates, or porous or cavernous dolomites or limestones. Fracture 
or fault zones also may act as reservoirs. The world’s maximum 
producers obtain their oil from cavernous limestones or dolomites; 
the steadiest and longest-lived wells are in medium-grained sand. 

5. Structure of reservoir rocks. —Structure usually has a profound 
influence on oil accumulation and production, the most advantageous 
positions being in the crests of domes or anticlines, or on the flanks 
of sealed or terraced monoclines. Lithology or other causes may 
locally produce exceptions to all rules of accumulation. 

B. ARTIFICIAL FACTORS. 

1. Price of oil. —The price of oil is the dominant factor governing 
the production of oil, especially as it relates to groups of wells, fields, 


PETROLEUM RESOURCES-ARNOLD. 


279 


districts, or States. The price may vary from 10 to 15 cents a barrel 
at the well, as at certain periods in the history of the Mexican or 
California fields, or it may range up to $2.50 per barrel, and in ex¬ 
ceptional cases much higher, when the demand is great and the sup¬ 
ply limited. Price of oil largely affects the other artificial factors, 
which may be summarized as follows: 

2. Depth of wells and time required to drill. —Production may be 
accelerated or retarded by the time required to drill wells. In some 
places wells can be put down in a week or 10 days; elsewhere it may 
take from one to two years to finish a well. In a shallow well dis¬ 
trict production can be increased quickly by a vigorous drilling pro¬ 
gram; in deep well areas much time and money may be necessary to 
increase or even sustain production. 

3. Distance separating wells. —Within a certain underground 
reservoir, the quantity of oil that ultimately can be recovered and 
the rapidity with which it may be produced are largely dependent 
on the distance separating the individual wells. The thicker the 
wells the quicker the recovery of the oil and the greater the expense 
of recovery. Wells may be spaced 25 feet apart or as near together 
as the derricks will stand, as in the congested Spindle-top field of 
Texas, or they may be separated by a distance of one-fourth mile or 
more. Ownership of property often determines the spacing of the 
wells, many small tracts under separate ownership tending toward 
congestion of development and rapidity of recovery. Conservation 
is best attained by single ownership of large bodies of land, so that 
development will be determined by the principle of recovering the oil 
at the least possible expense, that is, with the least number of wells. 

4. Condition of well , pump , etc. —The condition of the well, pump, 
and other physical properties involved in the winning of the oil 
greatly influences the production. Clean wells, efficient pumps, and 
energetic employees tend toward maximum production; sanded up or 
improperly perforated wells, leaky pumps, and inexperienced or 
careless employees militate against successful operation. 

5. Discovery of new fields. —The discovery of new fields is a most 
potent factor in oil production. The search for new fields is stimu¬ 
lated by high prices; their discovery usually results in a flush yield 
and a lowering of the price. Obviously, each new field raises the 
normal production to be expected from any district or State, and it 
is this factor of new territory which lends so much uncertainty to the 
oil business. 

6. Distance from market. —The distance from market of any field 
or group of wells often determines the rate of development and con¬ 
sequent production. Those fields nearest to market or favorable 


280 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1916. 


transportation facilities are usually quickly developed to their maxi¬ 
mum capacity, while fields farther away are often left for years 
without even being adequately prospected. 

7. Improvements' in development and recovery methods. —New 
methods of drilling and increasingly efficient methods of recovery are 
favorably affecting production in many fields. The most important 
advance in recent years has been along the line of increased use of 
compressed air in the recovery of oil, especially in California and 
Pennsylvania. 

8. Water complications. —“Water troubles” may be either natural 
or a combination of natural conditions and human carelessness or 
ignorance. Water causes the final ruin of practically all oil fields; it 
is the omnipresent and greatest menace of the producing fields. In 
most cases water troubles are inexcusable. Their results almost 
always are negative and sometimes irremediable. 

Oil in most fields of the United States and, in fact, throughout the 
world, occurs in inclined or sloping beds of sand or other porous 
rock, and these oil zones usually are overlain and underlain by water 
sands or zones which are separated from the oil zones by impervious 
clay, shale, or other strata. In these two cases the water is extraneous 
to the oil sands. These waters are called “ top ” and “ bottom ” 
waters, in accordance with their occurrence, respectively, above or 
below the oil zones. In a properly finished well the “ top ” water is 
cased off or cemented off before the well is drilled into the oil sand. 
The “ bottom ” water never is drilled into except by accident, in which 
event it is plugged off. With the “ top ” water shut off and the “ bot¬ 
tom” water untouched, the oil is produced practically free from 
water. Water, being heavier than oil and often also under a greater 
lr^drostatic pressure, will replace part or all of the oil at the point 
of ingress into the well if it is allowed to reach the oil sand. In this 
way it replaces the oil, in whole or in part, and thus lessens the 
amount of oil produced and increases its cost of recovery. Water 
also occurs indigenous to the oil sands in certain fields, but in this 
case it does not at first occupy the same part of the stratum as that 
occupied by the oil, but lies in the lower or “ down-slope ” portion of 
the sand, and the line marking the junction of the oil in the “ up- 
slope ” part of the bed and the water in the “ down slope ” part de¬ 
termines the limits of the productive territory. The water under 
these conditions is called “ edge ” water. Upon exhaustion of the oil 
by flowing or pumping, the “edge” water, through hydrostatic or 
other pressure, usually “ follows up ” and replaces the oil. The ap¬ 
pearance of the originally extraneous “ top ” water or “ bottom ” 
water in a well indicates a failure to exclude the water properly by the 
manipulation of casing, cement, or plugs. Such a condition usually 
can be remedied and the offending fluid kept out of the oil sand, 


PETROLEUM RESOURCES—ARNOLD. 


281 


although what has come in already may sometimes remain in the oil 
to a greater or less extent. The appearance of “edge” water in a 
well is another matter, for here the oil has been permanently replaced 
by the water, and, so far as the affected sand is concerned, the well 
can be considered as no longer productive. “ Edge ” water sometimes 
appears in a well in some particular sand, while other producing 
sands are free from water. In this instance, the “ edge” water sand 
is abandoned and cased off and the production continued from the 
other sands. 

Most of the water troubles are due to a failure to shut off the “ top ” 
water in the process of drilling. Wells, properties, and entire fields 
have been seriously damaged or entirely ruined by the water, some¬ 
times from only a few offending wells. This factor of water is, 
therefore, one of the most potent in oil production and at the same 
time the most uncertain. 

METHODS OF ESTIMATING FUTURE SUPPLY. 

Two methods of estimating the future production or supply of oil 
in any area or field are in use, one known as the saturation method, 
the other, the production curve method. 

SATURATION METHOD. 1 

The saturation method of computation involves finding the cubical 
contents of the reservoir, determining the degree of porosity of the 
volume, and then estimating the total, available, and net supply 
of oil contained under the area in cpiestion. By total supply is 
meant the total quantity of oil in the reservoir; by available supply 
is meant the quantity that theoretically can be recovered with ordi¬ 
nary methods in vogue; net supply is the quantity marketed after 
deducting for fuel used in development and operation, leakage, and 
other losses. 

Total supply depends on the volume and porosity of the reservoir 
and on the volume of free gas and of water which are included in the 
oil. The first factor usually can be approximated by taking the area 
involved and multiplying by the average thickness of the oil sand 
or zone. The porosity can be approximated from outcrop samples or 
drilling samples of the reservoir. Gas and water contents are un¬ 
certain, but in most instances can be disregarded for rough approxi¬ 
mations. Gas usually is in solution and the water only in the out¬ 
lying edges of the oil pools. Available saturation may range from 
0 to, possibly, 80 per cent, depending largely on the gas pressure 
and other factors, such as grain of reservoir, coherency, etc. From 
40 to 60 per cent of the total quantity ordinarily is recoverable. Of 

1 This method is described by Chester W. Washburne, Bull. A. I. M. E., No. 98, February, 
1915, pp. 4G9-471. 




282 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1916. 

this quantity possibly 10 per cent to 15 per cent is lost in production 
or used for fuel, so that of the total supply but 34 per cent to 54 per 
cent ordinarily is marketed. Many years may be required to make 
even this recovery. 

It is the writer’s belief that estimates based on the saturation method 
are much less reliable and satisfactory than those worked out through 
the production-curve method, but the former must be used for new 
or poorly developed fields and will be briefly described. 

The thickness of producing oil sands or oil zones varies from 2 feet 
in the Illinois field to over 200 feet in the California field. Total 
supply or saturation as marked by the porosity varies from a trace, 
in sands, up to 50 per cent in some exceedingly porous diatomaceous 
shale from California. Between 5 and 15 per cent is the average for 
sands, some, however, going as high as 30 per cent. An acre of 
ground covered with oil a foot deep (1 acre-foot) contains 7,758 bar¬ 
rels. This would be complete saturation for the 43,560 cubic feet. 
Assuming an average of 10 per cent saturation would give 775.8 bar¬ 
rels per acre-foot for normal conditions. On this basis a 5-foot sand 
would contain 3,879 barrels per acre, and a 50-foot sand 38,790 bar¬ 
rels. Actual yields of over 100,000 barrels per acre are known. 
Estimates of the average production per acre for the various States 
are given in Table III. Most of these figures are based primarily 
on the production-curve method, but a few are based on or checked 
by the saturation method. 

PRODUCTION-CURVE METHOD. 

General statement .—Estimating future production or supply by 
a plotting of hypothetical curves, based on actual figures in well- 
known areas or fields, is the safest method, as it involves factors 
which it is possible to obtain. Another thing in its favor from the 
standpoint of the producer and marketer of oil is that it is based 
on and has to do with actual “ net ” oil figures, instead of theoretical 
quantities. 

Basis of theoretical curve .—The theoretical curve shown in the 
diagram accompanying this article is based primarily on the yearly 
total production figures of New York and Pennsylvania. These 
figures cover a period of productivity of 54 years, longer by far 
than that of any other field in the United States. Furthermore, over 
this period this field has been subject to all of the vicissitudes from 
both natural and artificial causes that beset oil fields in general. The 
area involved in the Pennsylvania and New York field is greater 
than that in any other field in the United States, which is still 
another reason why the result should be conservative. 

The interesting part of the production curve is that following the 
period ol maximum yield. In some instances it is fairly safe to 


PETROLEUM RESOURCES—ARNOLD, 


283 

















































































































284 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1916. 


predict just when this period is reached, although usually a great 
divtvrgence of opinion prevails, due to whether the prophet is a pro¬ 
ducer or a consumer. As a rule, the crest of the production curve 
is not a sharp peak, but is represented by a more or less wavy dome, 
showing that the production remains near the maximum for several 
years. In the case of the Pennsylvania-New York curve, the period 
of high production extended over about 10 years; that of Ohio and 
West Virginia over 8 years; and that of Illinois over 2 years. Fol¬ 
lowing this period the production is more or less irregular, but in 
general decreases at a fairly regular rate, the rate of decrease, based 
on the previous year’s production, becoming gradually less and less 
as is indicated in the theoretical curve in the diagram. In figures 
this decrease may be tabulated thus, the basis of computation being 
the maximum yearly production for the field: 


Per cent of maximum production. 


At end of first 10 years_50 

At end of second 10 years_30 

At end of third 10 years_20 

At end of fourth 10 years_15 

At end of fifth 10 years_12. 5 

At end of sixth 10 years_10 


Average for 10 years 
Average for 10 years 
Average for 10 years 
Average for 10 years 
Average for 10 years 
Average for 10 years 


75 
40 
25 
17.5 
13. 75 
11. 25 


The usual development history in the period of high production 
is, first, a decrease of yield followed by increase in price, then re¬ 
newed development activity, with a resultant increase in }beld, a 
fall in price, and so on until the development reaches a point where 
the production of new wells fails to make up the decrease of the old, 
when the final period of decrease begins. 

ESTIMATED FUTURE PRODUCTION. 

The following table gives the estimated future production of 
petroleum in the United States, together with the approximate 
figures as to the proven and prospective oil-bearing areas, and a 
summary of the principal points regarding the occurrence and 
character of the oil. 

The figures of future supply take into account a certain per cent 
of the prospective oil area, as the curve on which they are based 
pertains to an area where new fields have been added from time to 
time as development progressed. In the case of Texas, Wyoming, 
etc., where the ratio of prospective area to proven area is high, the 
future supply may be considerably greater than that predicted if 
the bulk of the prospective land proves productive. 

COMPARISON WITH DR. DAY’S FIGURES FOR 19 08. 

Table IY is a comparison of the estimates given by Dr. Day for 
1908 with those by the writer for 1915. They are here presented by 
fields in order to correspond with Dr. Daj^’s divisions. 















Table III .—Past and estimated future 'production of petroleum in the United Stales. 


PETROLEUM RESOURCES—ARNOLD, 


285 


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Table IV .—Estimated total production of the United States, by fields. 


286 


ANNUAL REPORT SMITHSONIAN INSTITUTION, 1916. 


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PETROLEUM RESOURCES—ARNOLD. 


287 


Comparing the writer’s estimates with those of Dr. Day, it is at 
once apparent that the estimates for the older eastern fields have 
been reduced while those for the western fields have been increased. 
This is especially true for the Mid-Continent field, in which there 
was little development at the time Dr. Day’s figures were compiled. 
In the case of California 1 * it has been found that the available satura¬ 
tion is less than was expected during the early history of the field. 
At the time the first estimates were made the field gas pressure was 
high and water trouble had not become serious. With the lapse of 
time it has become evident that a reduced gas pressure and water infil¬ 
tration necessitate materially cutting the original figures. 

At the present rate of consumption of approximately 265,000,000 
barrels per year, an estimated supply of 5,763,100,000 barrels would 
last only, approximately, 22 years. However, as the total produc¬ 
tion of the United States will gradually decrease from year to year, 
it is believed that the total available supply will spread out over a 
period of from 50 to 75 years. The price of oil, which now ranges 
from 40 cents to $2 per barrel (average, 95 cents), depending on the 
locality and grade of the product, probably w 7 ill increase to figures 
approximating $1 per barrel for fuel oil and possibly $5 or more for 
the lighter grades. All other factors being equal, a barrel of fuel 
oil as compared with coal on the Pacific coast is worth to-day 
93 cents. Even were oil to be used only as a fuel, the tendency would 
be for it to rise in price until it reached a point set by the value of 
coal in the same regions. As oil has so many points in its favor, as 
regards ease of handling, cleanliness, etc., it is quite evident that 
eventually it will be sold at a higher price than is warranted by its 
heat value as compared with that of coal. 

Before the free natural petroleum in the earth is exhausted the 
oil shales of Colorado, Utah, California, and other States will have 
begun to be utilized as a source of petroleum. Also artificial oil 
made from animal and vegetable waste probably will be available to 
take its place. Even at the present time the necessities of war have 
led certain of the European governments to utilize various substi¬ 
tutes for petroleum and its derivatives, the substitutes in general 
being made from organic substances. 

In conclusion, the writer might repeat what often has been pointed 
out by conservationists, that oil as far as possible should be used for 
those purposes for which we have no other substitute, namely, for 
lubricants, refined derivatives, etc., and not for fuel. If used for 
fuel, it should not be in connection with the wasteful steam engine, 
but in the Diesel engine and similar types, which are so much more 
efficient that their use doubtless will become more and more general 
as time goes on. 

1 Dr. Geo. Otis Smith discusses the duration of California petroleum resources in Min. 

Res. U. S. for 1910, Pt. II, p. 416, et seq. 









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